1. Field of the Invention
The present invention relates to an inductive power supply system and an intruding metal detection method thereof, and more particularly, to an inductive power supply system and an intruding metal detection method thereof for simultaneously processing an inductive power transmission operation and detecting whether an intruding metal exists.
2. Description of the Prior Art
In the prior art, an important issue for an inductive power transmission system is to adaptively recognize whether a chargeable device is disposed nearby a transmission coil for an inductive power transmission operation, which is similar to the principle of the induction cooker to generate high-power electromagnetic energy for the inductive power transmission operation. During the operation, when the high-power electromagnetic energy is received by an intruding metal, the intruding metal is heated extra dangerously. In such circumstances, producers developing the inductive power transmission operation have dedicated research into the induction technique with capable object-recognition. Generally, an inductive coil utilized to set up a wireless signal transmission operation between a power receipt end and a power transmission end has been adopted, so as to utilize a receipt coil of the power receipt end to return information signals and utilize a transmission coil of the power transmission end for receiving the information signals. Thus, a relatively effective wireless transmission has been developed for the inductive power transmission operation as well as the wireless signal transmission operation between the power receipt end and the power transmission end.
However, when the producers want to simultaneously process the inductive power transmission operation and the wireless signal transmission operation, both operations are easily interfered with by surrounding signals since the inductive power transmission operation utilizes a relatively high-power carrier wave for transmission, which results in difficulty of operating the wireless signal transmission operation. Alternatively, combination of another solution of wireless signal transmission, such as infrared, blue tooth, RFID or WiFi, and the original inductive power transmission operation has been provided as well. Nevertheless, additional wireless transmission modules are installed to increase production cost, and accordingly, lowers the consumers' popularity. Therefore, the popularity still tends to choose the inductive coil with higher efficient transmission mechanism to process the inductive power transmission operation as well as the wireless signal transmission process.
Noticeably, during processing the inductive power transmission operation as well as the wireless signal transmission operation, a detection signal is utilized for the receipt power end to correctly recognize the chargeable device, so as to process the inductive power transmission operation. In other words, when the user disposes an intruding metal, such as coins, keys or paper clips, which cannot return the wireless information signals, the transmission power end will not process the inductive power transmission operation after transmitting the detection signal with no correspondingly receipt from the receipt power end, so as to avoid the danger of heating the intruding metal. However, the above operation has another potential problem. When the transmission power end detects existence of the chargeable device and there is also an intruding metal partially blocking an interaction area between the transmission coil and the receipt coil, the transmission power end and the receipt power end still utilize the other area without blocking for the wireless signal transmission operation, such that the intruding metal will receive partial electromagnetic energy to be heated dangerously.
For the above problems, the Taiwan patent publication No. 201143250 “Input parasitic metal detection” has disclosed a solution, which analyzes a power consumption value between an input power of the transmission power end and an output power of the receipt power end, so as to determine whether an extra power consumption value happens and correspondingly stops the inductive power transmission operation for safe concerns. However, the extra power consumption value has other possible contributions rather than the intruding metal. For example, a relative position shift between the transmission coil and the receipt coil can cause the occurrence of the extra power consumption value. Therefore, the prior art has to predetermine relative extra power consumption information related to the transmission/receipt coil or other power conversion elements. Alternatively, the user can thoroughly measure the power consumption information caused by intruding metal interacting with all the power conversion elements, and accordingly, take the premeasured power consumption information into the practical operation as the comparison. However, the premeasured power consumption information is highly related to driving voltages, characteristics or detail specs of the power conversion elements. If the user changes one of the power conversion elements, the corresponding parameters need to be reset without flexibility, which seems to be hard for practical determination of the existence of the intruding metal. Besides, relative detection circuits are needed to be installed at the transmission power end and the receipt power end, so as to accurately measure passing current/voltage changes of the transmission/receipt power end for the power consumption information. However, the relative detection circuits have their limitation to obtain the practical changes of the power consumption information, and one more wireless transmission operation is necessary for the power receipt end to transmit the measured current/voltage changes back to the transmission power end for following calculations, which may result in potential errors in determination of the existence of the intruding metal.
Therefore, it has become an important issue to provide an inductive power supply system and an intruding metal detection method thereof for simultaneously processing an inductive power transmission operation and detecting whether an intruding metal exists.